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Photocatalytic CO2 reduction holds promise as a future technology for the manufacture of fuels and commodity chemicals. However, factors controlling product selectivity remain poorly ...understood. Herein, we compared the performance of a homologous series of Zn-based layered double hydroxide (ZnM-LDH) photocatalysts for CO2 reduction. By varying the trivalent or tetravalent metal cations in the ZnM-LDH photocatalysts (M = Ti4+, Fe3+, Co3+, Ga3+, Al3+), the product selectivity of the reaction could be precisely controlled. ZnTi-LDH afforded CH4 as the main reduction product; ZnFe-LDH and ZnCo-LDH yielded H2 exclusively from water splitting; whilst ZnGa-LDH and ZnAl-LDH generated CO. In-situ diffuse reflectance infrared measurements, valence band XPS and density function theory calculations were applied to rationalize the CO2 reduction selectivities of the different ZnM-LDH photocatalysts. The analyses revealed that the d-band center (εd) position of the M3+ or M4+ cations controlled the adsorption strength of CO2 and thus the selectivity to carbon-containing products or H2. Cations with d-band centers relatively close to the Fermi level (Ti4+, Ga3+ and Al3+) adsorbed CO2 strongly yielding CH4 or CO, whereas metal cations with d-band centers further from the Fermi level (Fe3+ and Co3+) adsorbed CO2 poorly, thereby yielding H2 only (from water splitting). Our findings clarify the role of trivalent and tetravalent metal cations in LDH photocatalysts for the selective CO2 reduction, paving new ways for the development of improved LDH photocatalyst with high selectivities to specific products.
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•FeS2/PS system could remove CBZ efficiently.•The existence of Fe(IV) in the FeS2/PS system were successfully identified.•Neutral and alkaline conditions were more conducive to the ...formation of Fe(IV).•Heterogeneous and homogeneous reactions simultaneously occurred for Fe(IV) generation.•Fe(IV), SO4− and OH jointly contributed to CBZ degradation.
To investigate the reactive species generated in the pyrite (FeS2)-activated persulfate (PS) process, typical antiepileptic carbamazepine (CBZ) was chosen as the target contaminant and then degraded in the FeS2/PS system. Optimum operating conditions were determined to be 0.5 g·L−1 of FeS2 dosage and 1 mM of PS concentration via response surface method analysis. Different from previous conclusions that Fe(II) reacted with PS to directly generate sulfate radical (SO4−), tetravalent iron Fe(IV) was identified as a reactive intermediate employing PMSO probe, and the highest steady state concentration of Fe(IV) was calculated to be 5.62 × 10−4 μM at pH 7.0. Conversely, the highest steady state concentrations of SO4− and hydroxyl radical (OH) occurred at pH 3.5 as well as the complete removal of CBZ (21.16 μM). Alcohol quenching experiment and competitive oxidation experiment confirmed that SO4−, OH and Fe(IV) all contributed to CBZ degradation. According to X-Ray photoelectron spectroscopy spectra and density functional theory calculations, it demonstrated the electron transfer between the S atoms and the Fe site which absorbed PS molecule, thus contributing to the formation of heterogeneous Fe(IV). In the proposed CBZ degradation pathways, Fe(IV) gave rise to the primary product 10,11-epoxycarbamazepine formation, and radical species continued to degrade and mineralize 10,11-epoxycarbamazepine.
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•Cerium(IV) complexes supported by O-, N- and C-donor ligands are reviewed.•Chelating O-donor ligands can stabilize the +IV state of cerium.•Cerium(IV) can form multiple bonds with ...carbon, nitrogen and oxygen atoms.•Cerium(IV) oxo complexes exhibit interesting nucleophilic and redox reactivity.
Despite widespread applications of tetravalent cerium compounds in organic synthesis and catalysis, the coordination and organometallic chemistry of cerium(IV) complexes has not been well explored, due, in part, to the high oxidizing power of Ce(IV). Using chelating O-donor supporting ligands, stable tetravalent cerium complexes bearing various ligand functionalities have been isolated, thus making it possible to investigate the reaction chemistry of cerium(IV) complexes systematically. This review summarizes the recent developments of the coordination chemistry of cerium(IV) complexes bearing O-, N-, and C-donor ligands. Special attention will be directed to cerium(IV) complexes supported by a tripodal oxygen ligand.
We previously reported the efficacy of prime-boost vaccination using three tetravalent (T) dengue vaccines, DNA (TDNA), purified inactivated vaccine (TPIV), and live attenuated vaccine (TLAV). We ...demonstrated that the TPIV/TLAV prime-boost vaccination yielded the highest and most durable neutralizing antibodies and 100% protection to all 4 serotypes of dengue virus in rhesus macaques. This study compares gene transcription, T and B cell responses elicited by these prime-boost combinations in rhesus macaques.
This study shows that the TLAV vaccine increased the expression of the innate immune genes, DDX58 and TLR7, IL1A, IL1B, TNF, CXCL8, CXCL10, IRF1, IRF7, and IFNB, more robustly as compared to TDNA and TPIV vaccines. Overall, two doses of TDNA and one dose of TLAV efficiently elicited a T cell IFNγ response to PrM/E with a comparable magnitude. Compared to TDNA vaccine, the TLAV vaccine elicited additional IFNγ response to C, NS1, NS3, and NS5. The TPIV vaccine alone produced poor IFNγ response; however, the TLAV significantly boosted its IFNγ response. The T cell response repertoire associated with TPIV/TLAV prime-boost was to both the structural C/PrM/E and NS proteins, and the T cells were multifunctional as the CD4+ T cells produced IFNγ, TNF α, and IL2 and the CD8+ cells produced TNF α and IFNγ. Opposite to the pattern of CMI, the TPIV vaccine alone elicited the highest BMem compared to the other two vaccines, which continuously remained as the highest after boosting.
In summary, the TDNA and TLAV vaccines elicited a strong T cell response whereas the TPIV vaccine elicited a superior BMem. The T cell response of the TPIV vaccine was significantly boosted by the TLAV vaccine. The elevated T cell response may have provided T cell help for a sustained antibody response for TPIV/TLAV vaccines, which is required for a protective immunity against a live virus challenge.
The goal of the present work was to fabricate a new low-cost, easy-to-prepare, dual-channel fluorescence chemosensor comprised of acridine-diphenylacetyl moieties (NDA) to enable remarkable Sn4+ ...detection in water and biological medium. The resulting NDA–Sn4+ complex was utilized for the distinguished identification of Cr2O72- ions from other anions and biomolecules. These investigations involve the absorption, fluorescence, and electrochemical methods for the detection of Sn4+ and Cr2O72- ions in pure water. The mechanism for NDA-mediated Sn4+ detection was experimentally determined by FT-IR, NMR titrations, mass (ESI) analyses, and DFT calculations. The obtained results indicate that the NDA chemosensor possessed excellent performance characteristics including good water solubility and compatibility, quick response time (less than 10 s), high sensitivity (Sn4+ = 0.268 μM and Cr2O72- = 0.160 μM), and selectivity against coexisting metals, anions, amino acids, and peptides. The chemosensor NDA induced negligible toxicity in live cells and was successfully utilized as a biomarker for the tracking of Sn4+ in human normal and cancer cells. More importantly, NDA demonstrates distinguished recognition of Sn4+ in human cancer cells rather than in normal live cells. Additionally, NDA was shown to act as a mitochondria-targeted probe in FaDu cells.
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•A new acridine-based chemosensor NDA for Sn4+ and Cr2O72- ions was developed.•NDA displays higher selectivity over other coexisted ions and biomolecules.•NDA shows distinct superiority in real water samples and bioimaging analysis.•NDA demonstrated as a mitochondria-targeted chemosensor in FaDu cells.
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•F–Zr:Fe2O3/FTO photoanode was synthesized via facile dual elemental co-doping.•A remarkable Jph of 1.91 mA cm−2 at 1.23 VRHE has been obtained without catalyst support.•Zr-doping ...promotes fast transfer of photogenerated electrons within bulk hematite.•F-doping boosting the surface charge (holes) injection efficiency at the SEI.•Synergistic effect of dual elemental co-doping promotes hole transfer via surface states.
Dual elemental doping strategies were employed in this study to fabricate fluorine and zirconia co-doped hematite (F–Zr:Fe2O3/FTO) photoanodes. Such F–Zr:Fe2O3/FTO photoanodes had a (110)-oriented structure with a remarkable photocurrent density of 1.91 mA cm−2 without any catalyst support at water oxidation potential of 1.23 VRHE. The enhancement in net photocurrent density was attributed to the synergistic effect between the two doping elements. When in situ doped Zr4+ ions were used to substitute iron ions, they increase photogenerated free electrons within the bulk hematite and resulted in lower bulk charge transfer resistance, and a minimal concentration of F was doped into hematite lattice, it would go into the oxygen site rather than the iron site, resulting in more positive charges on iron site. The charge compensation contributed to reduced recombination of free electron–hole pairs and improved surface charge injection efficiency at the semiconductor–electrolyte interface by promoting hole transfer via surface states.
Background: COVID-19 vaccines that offer broad-spectrum protection are needed. We aimed to evaluate the safety and immunogenicity of multivalent vaccines, SCTV01E and SCTV01C, and compare them with ...an inactivated vaccine. Methods: In the phase 3 trial (ClinicalTrials.gov: NCT05323461), adult participants previously vaccinated with Sinopharm's inactivated SARS-CoV-2 vaccine (BBBIP-CorV) were assigned to receive one booster dose of BBBIP-CorV, 20 μg SCTV01C, or 30 μg SCTV01E. The primary endpoint was to evaluate the geometric mean titers (GMT) of neutralizing antibody (nAb) against the Delta and Omicron BA.1 variants on day 28 after injection. Additional endpoints included GMTs of nAb against Delta (B.1.617.2) and Omicron BA.1 variants on day 180, GMTs against BA.5 on day 28, as well as solicited adverse events (AEs) within seven days, unsolicited AEs within 28 days, and serious AEs, AEs of special interest within 180 days after vaccination. Findings: Between May 30, 2022 and October 28, 2022, a total of 1351 participants were randomized to BBBIP-CorV, SCTV01C, or SCTV01E in a 1:1:1 ratio, with immunogenicity assessments performed on the first 300 participants. For BBBIP-CorV, SCTV01C, and SCTV01E groups, the day 28 GMTs of neutralizing antibody against Omicron BA.1 were a 2.38-, 19.37-, and 28.06-fold increase from baseline; the GMTs against Omicron BA.5 were 2.07-, 15.89- and 21.11-fold increases; the GMTs against Delta variants were 1.97-, 12.76-, and 15.88-fold increases, respectively. The day 28 geometric mean ratio (GMR) of SCTV01C/BBIBP-CorV for Omicron BA.1 was 6.49 (95% CI: 4.75, 8.88), while the GMR of SCTV01E/BBIBP-CorV was 9.56 (95% CI: 6.85, 13.33). For the Delta variant, the day 28 GMR of SCTV01C/BBIBP-CorV was 6.26 (95% CI: 4.78, 8.19), and the day 28 GMR of SCTV01E/BBIBP-CorV was 7.26 (95% CI: 5.51, 9.56). On Day 180, the GMTs against Omicron BA.1 were 2.80-, 9.51-, and 15.56-fold increase from baseline, while those against Delta were 1.58-, 5.49-, and 6.63-fold for BBBIP-CorV, SCTV01C, and SCTV01E groups, respectively. Subgroup analyses showed that SCTV01C and SCTV01E induced uniformly high GMTs against both BA.1 and BA.5, demonstrating its superiority over BBIBP-CorV, regardless of baseline GMT levels. Safety and reactogenicity were similar among the three vaccines. Most AEs were Grade 1 or 2. There were 15 ≥Grade 3 AEs: 6 in the BBIBP-CorV group, 4 in the SCTV01C group and 5 in the SCTV01E group. No SAE was reported and one grade 1 AESI (Bell's palsy) was observed in SCTV01C group. Interpretation: A booster dose of the tetravalent vaccine SCTV01E consistently induced high neutralizing antibody responses against Omicron BA.1, BA.5, and Delta variants, demonstrating superiority over inactivated vaccine. There is evidence to suggest that SCTV01E may have GMT superiority over bivalent vaccine SCTV01C against Delta, BA.1 and BA.5 variants. Funding: This study was sponsored by Sinocelltech Ltd., and funded by the Beijing Science and Technology Planning Project Z221100007922012 and the National Key Research and Development Program of China 2022YFC0870600.
Lithium-zinc-germanate glass-ceramics doped with Mn ions are synthesized by volume crystallization method. Structural studies show nucleation of different forms of lithium germanate crystals ...depending on the isothermal treatment regime of the initial glass. With the increase of the heat treatment temperature and the lithium content in the initial glass, the GeO4 /GeO6 ratio in the nucleated crystalline phases increases. The initial distribution of Mn2+/Mn3+/Mn4+ is defined by the Li2O/ZnO ratio in the glass composition: the ratio growth increases the contribution of Mn4+ over the Mn2+ and Mn3+. Low-temperature heat treatment of initial glass leads to uprise of intense red emission of Mn4+ ions in the octahedral environment. High-temperature heat treatment leads to occurrence of intense green emission related to Mn2+ ions in a tetrahedral environment. Discussions on all transformations of symmetry, the crystal field strength of Mn ions’ environment and their valence state based on the results of optical spectroscopy, ESR and XRF studies are provided. The maximum quantum yield of red luminescence is 61%, and of green luminescence is 23%. The synthesized glass-ceramics can be used as a luminescent converter of the UV LED radiation with the maximum energy efficiency of 20%.
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Optical temperature sensors based on photoluminescent materials have received extensive attention for their non-contact superiority. The traditional optical thermometry usually utilizes rare earth ...doped phosphors with thermal coupling levels to realize Boltzmann equilibrium. However, high temperature sensitivity and good signal resolution cannot be satisfied at the same time based on this strategy due to the photoluminescence quenching at high temperature. Herein, Eu3+/Mn4+ co-doped Li4AlSbO6 double perovskite phosphor is introduced as recommendable optical thermometry. Under 465 nm blue light excitation, the phosphor exhibits Eu3+ (611.5 nm) and Mn4+ (675 nm) emissions in the red and near-infrared ranges, respectively. Due to the different temperature-dependence optical behaviors of Mn4+ and Eu3+ in the range of 80 K–460 K. The highest relative sensitivity Sr of LIR based on 2E-4A2 (675 nm)/5D0-7F2 (611.5 nm) was 2.47% K−1. In addition, the highest absolute sensitivity Sa and relative sensitivity Sr obtained based on the average decay lifetime ratio of Mn4+ and Eu3+ are 0.134 K-1 and 3.07% K−1, respectively. These results indicate that Eu3+/Mn4+ co-doped Li4AlSbO6 is one kind of remarkable optical thermometry with high sensitivity.
•Eu3+/Mn4+ co-doped Li4AlSbO6 phosphor presented red and deep-red emission.•The highest relative sensitivity Sr based on lifetime ratio is 3.07% K−1 at 416 K.•The phosphor is beneficial for high temperature sensing.
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